The major research objectives of this investigative program are: 1) to study the control mechanisms involved in regulating the secretion of the various pituitary and pancreatic hormones, and 2) to determine whether any alterations in these control mechanisms exist in patients with diabetes mellitus and to evaluate how these alterations, through the action of such intermediary plasma components as somatomedin, might influence the course of this disease. Utilizing the radioimmunoassay method to measure the growth hormone, TSH, LH, FSH and insulin, the control mechanisms regulating the secretion of these hormones in normal subjects and diabetic patients will be studied. The same hormones will be measured in th pituitary glands and plasma of rats maintained in a variety of metabolic or nutritional states, and in response to various agents known to stimulate or suppress the secretion of some of the hormones being studied. By a combination of in vivo and in vitro studies of pituitary hormone release, measuring both total and precursor-labelled hormone concentrations, the rate of synthesis as well as release of these hormones will be determined.